The invention relates to a changeover device for an installation for recovery of the gases and fumes proceeding from a tilting converter.
French Pat. No. 2,366,366 and corresponding U.S. Pat. No. 4,128,230 a device which enables the recovery of the gases and fumes proceeding from a converter which tilts about a horizontal axis, whether this converter is in vertical or inclined position, i.e., during refining of the steel contained in the converter and during charging with melt or with scrap or during pouring of the steel, respectively.
It is in any case necessary to recover the gases and fumes escaping from the converter, so as to prevent them from escaping into the atmosphere of the steel plant.
The recovery installation described in the above mentioned patents includes an enclosure having dimensions sufficient to accommodate the tilting movements of the converter, enveloping the latter about at least that portion of it which is situated above the horizontal plane containing the axis of tilt of the converter. The enclosure is equipped with doors to permit charging of the converter, and it is connected to a fixed suction duct situated above the spout of the converter in the vertical position, this duct, or main suction duct, enabling the recovery of the gases escaping into the enclosure when the converter is in its vertical service position. A means for regulating the suction enables solely the gases escaping from the converter to be drawn off, to the exclusion of the air which may penetrate into the enclosure.
On the contrary, when the converter is in inclined position, the suction regulating means remains in a fixed position, i.e., the position which corresponds in general with maximum suction.
Certificate of Addition No. 2,402,708 to French No. 2,366,366, also discloses a recovery device which includes, besides the main suction duct connected to the enclosure, a secondary suction duct generally connected to a hood situated outside the enclosure and underneath which the spout of the converter is disposed in inclined position, permitting the recovery of the gases at the time of charging the converter.
The main duct and the secondary duct are connected to one and the same suction device by way of a changeover device which enables the suction to be exerted either through the main duct or the secondary duct.
At the time of tilting of the converter the changeover device must be manipulated in order to place the secondary suction duct into service. The changeover device must therefore be extremely reliable in operation and must enable very good isolation of the secondary suction duct with respect to the main suction duct even in the case of poor operation of the control mechanism for the changeover device.
The very large size of the suction ducts employed for the recovery of converter gases demands on the other hand the employment of closure pieces which are themselves of very large dimensions, for the formation of the changeover device. Hitherto valves or dampers have not been known which enable the functions detailed above to be fulfilled under the best conditions.